CN108737267B - A Routing Algorithm Based on SDN and ICN Satellite Network Architecture - Google Patents

Abstract

The invention discloses a routing algorithm based on SDN and ICN satellite network architecture, comprising the following specific steps: step 1, dividing virtual nodes; step 2, designing FIB and PIT tables based on virtual nodes; step 3, updating FIB table mechanism; step 4 , when the ground node initiates a request to the low-orbit switch node, the switch node matches the request according to the flow table, and if the match is successful, it forwards the request directly; otherwise, the node matches the request type according to the flow table and extracts the source, destination IP address or virtual node according to the request type information, the controller executes a virtual node-based routing algorithm. The routing efficiency of the algorithm and the aggregation performance of the controller to the request have obvious advantages.

Description

A Routing Algorithm Based on SDN and ICN Satellite Network Architecture

technical field

The invention relates to the field of satellite communication networks, in particular to a routing algorithm based on SDN and ICN satellite network architecture.

Background technique

At present, human beings have entered the information age, and information is called the core driving force of current social and economic development. The traditional terrestrial information equipment and transmission system can no longer meet the complex information needs. Compared with terrestrial information transmission, spatial information transmission has obvious advantages in coverage area, access speed, efficiency, real-time performance, and accuracy. An integrated network that makes full use of the advantages of space information transmission and terrestrial information transmission can meet the increasingly complex information needs.

With the development of the space-earth integrated network, the multi-layer satellite network routing technology has become an urgent problem to be solved, and the high operating speed of the satellite nodes makes the traditional static routing algorithm not well applied to the satellite network. The network cannot meet the needs of time transmission of big data, and the simple information center satellite network cannot realize data return or requires forwarding nodes with strong routing capabilities.

SUMMARY OF THE INVENTION

In view of the limitations of the prior art, the present invention designs a virtual routing algorithm based on virtual nodes. The algorithm is based on the satellite network architecture of SDN and ICN technology (hereinafter referred to as SDICSN architecture) and introduces the idea of information center into the software-defined satellite network architecture. , the satellite network management is simplified through the separation of SDN control and control, and the response speed of network requests is improved by using the characteristics of ICN cache. At the same time, the GEO satellite node is used as the SDN controller to realize the ICN request and data return through the global high-orbit controller. dynamic routing.

The SDICSN architecture consists of a terrestrial network and a satellite network. The ground network is divided into several Autonomous Systems (AS) according to the characteristics of the area. Each AS is managed by a Name Routing System (NRS) controller, and the controllers exchange network status information through the northbound interface. For the ICN request in the ground network, when the Interest packet of the content request reaches the OpenFlow switch node, if the switch can identify the Interest packet, the request is forwarded according to the flow table of the switch; otherwise, the forwarding path is generated by the NRS controller according to the PIT and FIB. and deliver it to the corresponding switch. For traditional IP-based requests, the NRS controls the generation of forwarding paths based on source and destination IP addresses.

In order to achieve the above object, the technical solution of the present application is: a routing algorithm based on SDN and ICN satellite network architecture, characterized in that it includes the following specific steps:

Step 1, divide virtual nodes;

Step 2, design FIB and PIT table based on virtual nodes;

Step 3, update the FIB table mechanism;

Step 4: When the ground node initiates a request to the low-orbit switch node, the switch node matches the request according to the flow table, and directly forwards the request if the match is successful; otherwise, the node matches the request type according to the flow table and extracts the source, destination IP address or Virtual node information, the controller executes the routing algorithm based on the virtual node.

Further, the specific way of dividing virtual nodes in step 1 is:

R1: Select the prime meridian as the starting line, and take the positive direction from south to north and from west to east;

R2: According to the number of orbital planes N and the number of satellites M in each orbital plane, divide the earth sphere into 2*N*M logical grids, each grid is a virtual node;

R3: Each virtual node is uniquely determined by the number <n,m> of the vertex in the lower left corner;

R4: After the virtual node network is determined, the label of each virtual node uniquely corresponds to a set of <longitude, latitude> values, namely

Further, in an inclined orbit constellation, looking down from above the North Pole, the right ascension of the ascending nodes of the N orbital planes is evenly distributed in a circle of 2π in the plane where the equator is located; for the Walker constellation with the parameter i:T/N/F, Assuming that the ascending node right ascension at the initial moment of the first orbital plane is Ω ₁ , and the initial phase angle of the satellite node numbered 1 in the first orbital plane is ω _1,1 , then the ascending node right ascension of all satellite nodes in the constellation is and the phase angle are calculated by the following formulas:

In the formula, T is the total number of satellites on the Walker constellation; F is the phase factor.

Further, the design of FIB and PIT tables based on virtual nodes in step 2 is as follows: according to the virtual node topology strategy, the satellite network is abstracted into a large switching node, and the source and destination nodes of the ground request are fixed relative to the satellite network.

Further, the virtual node mark where the CS node is located is added to the relationship record between the content of the FIB table and the storage node, and the virtual node mark where the port is located is added to the PIT table in the relationship record between the content and the forwarding port; at the same time, the FIB and PIT tables are controlled by the high rail. Server management, the update of the PIT table is dynamically updated with the arrival of the request and the return of the data.

Further, the present application also includes: Step 5: after generating the forwarding path, the controller sends it to the relevant switch node, and the switch node performs the forwarding action; when the data is returned, the controller generates the return of the data object according to the PIT table. path, and perform content caching according to the cache replacement policy while adding records to the FIB table.

Further, in step 3, a mechanism combining event-driven and polling is used to update the FIB table mechanism, specifically: in the event-driven mechanism, when the request data is returned to the satellite node, the controller actively updates the FIB table; When a cache replacement operation is performed to replace a certain content, the switch actively announces the change, and the controller updates the FIB table; the controller collects the resources of the switch node by polling. After the node initiates the polling request, after the timer expires and no ACK is received, the controller considers the node to be invalid, and the controller updates the FIB table and marks the related content name record as invalid; when the FIB table has a record replacement The marked records will be replaced first.

As a further step, the routing algorithm based on virtual nodes is as follows: Assuming that the initial processing capabilities of all satellite nodes are the same, and each satellite node keeps links in the directions of the four domains, there are:

S1: Calculate the maximum traffic D _<n,m> of the virtual node:

S2: Calculate the virtual node load rate γ _<n,m> ;

where data(j) represents the data transmission volume of satellite node j per unit time;

S3: Calculate the link weight w _<n,m> , the link weight reflects the ability of intra-orbital and inter-orbital interplanetary links to transmit data;

S4: Define the routing matrix.

As a further step, S3: Calculate the link weight w _<n,m> specifically:

The first part is the reciprocal of the end-to-end transmission time of 1bit data, L _<n,m> is the length of the interstellar link <n,m>, C is the speed of light transmitted in the vacuum; the second part is the interstellar link <n,m> bandwidth availability, s _<n,m> is the remaining bandwidth of the interstellar link <n,m>, B is the maximum bandwidth of the interstellar link <n,m>; α is the link weight self Adaptation factor, whose value range is between (0, 1), the controller automatically adjusts the value of α according to the link bandwidth utilization.

As a further step, S4: Define the routing matrix:

1) If v=v ₁ , o=o ₁ , the transmission path is generated in a matrix with virtual node coordinates <n ₁ , m ₁ > and <n ₂ , m ₂ > as diagonal vertices;

2) If v=v ₂ , o=o ₁ , at this time, due to the characteristic that the links in the track form a loop, in the logical network, the routing matrix is transmitted in the vertical direction, and the transmission path is still in the virtual node coordinate <n ₁ , m ₁ > and <n ₂ , m ₂ > are generated in the matrix of diagonal vertices;

3) If v=v ₁ , o=o ₂ , at this time, the routing matrix is transmitted in the horizontal direction;

4) If v=v ₂ , o=o ₂ , at this time, the routing matrix is transmitted in a circular direction in both the vertical direction and the horizontal direction.

Compared with the prior art, the present invention has the beneficial effect that the algorithm generates a routing matrix through the relative orientation of the source and destination nodes in the satellite network, thereby reducing the complexity of routing calculation. The routing efficiency of the algorithm and the aggregation performance of the controller to the request have obvious advantages.

Description of drawings

Fig. 1 is a schematic diagram of virtual node division;

Fig. 2 is the dynamic update schematic diagram of FIB table based on event-driven and polling mechanism;

Fig. 3 is the virtual node routing state diagram of adaptive ICN and IP request;

Fig. 4 is a routing matrix logic diagram;

Figure 5 is a diagram showing the relationship between the request delay and the number of requests;

FIG. 6 is an explanatory diagram of a request aggregation degree;

FIG. 7 is a graph showing the relationship between the request hit rate and the number of requests;

FIG. 8 is an explanatory diagram of the update speed of the FIB table.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

Example 1

This embodiment provides a satellite network architecture based on SDN and ICN technologies, including: an application layer, a control layer, and a forwarding layer; the application layer implements services such as content caching, name resolution, message routing, and security; the application layer and control layer The northbound interface between the layers realizes the deployment of services; the control layer is layered and distributed, and the internal controllers communicate through the east-west interface, and each controller provides an open interface to realize the application layer to the controller. Programmability Function; the forwarding layer includes low-orbit OpenFlow-based satellite nodes and terrestrial OpenFlow switches, this layer realizes message forwarding according to the flow table issued by the control, and at the same time adds the function of caching the returned content. Each controller includes: a network topology management module, a routing management module, and a content management module; the network topology management module includes: a link state monitoring module and a network topology management module; the routing management module includes: a network Traffic management monitoring module, name-based routing calculation module, forwarding information base FIB management module and pending request table PIT management module; the content management module includes a content fragmentation management module, a name resolver and a content cache management module; control The controller uses the OpenFlow protocol to control the forwarding device through the secure channel of the OpenFlow switch. In this architecture, the controller of the ground network adopts a hierarchical distributed control method, which is divided into several autonomous areas (AS) according to the regional characteristics, and each autonomous area is managed by a Name Routing System (NRS) controller , the controllers exchange network status information through the northbound interface. The satellite network in this architecture adopts a double-layer orbit design, in which three synchronous satellites are used as controllers to realize global real-time monitoring, and the low orbit adopts the Walker constellation to achieve global coverage.

Preferably, the architecture adopts the method of covering the IP protocol to identify the ICN request, and uses the IF (ICN-Flag) value to distinguish the request type; for the ICN request, the Options field of the IP protocol is used to carry the content name information.

Preferably, the entire satellite operation cycle is divided into several time slices; the satellite controller periodically detects changes in the satellite network topology; thereby predicting in advance whether the data transmission path needs to be changed, thereby ensuring that the data packet returns will not be affected by the satellite network. interrupted by the dynamics.

When the ICN client initiates a request, it determines whether the content needs to be forwarded through the satellite network according to the status information of the requested content in the controller, so as to track the forwarding process of the request through the ground or high-orbit controller; when the content returns, the OpenFlow on the return path Nodes cache content according to a cache replacement policy. When a satellite node on the data return path fails and data is interrupted, its direct predecessor satellite node reports error information to the controller after the ACK times out, and the controller regenerates the data return path and avoids the faulty node.

In this embodiment, the SDICSN architecture is proposed to solve the problems of large transmission delay of video and other big data, and complex satellite network control and new service deployment in the traditional space-ground integrated network. By introducing SDN and ICN technologies, on the one hand, the SDN framework is used to simplify the control of the integrated space-earth network and improve the efficiency of network service deployment; It has the characteristics of high sensitivity and selective caching, so as to improve the overall performance of the integrated network of heaven and earth.

Example 2

This embodiment provides a routing algorithm based on the SDN and ICN satellite network architecture. For the design of a low-orbit constellation, the two basic parameters of the constellation are the number of orbits N and the number of satellite nodes in the same orbit M, accordingly Virtual nodes can be divided. Since the parameters of the satellite network are designed in advance, after the constellation parameters are determined, the geographic location information of each virtual node is determined accordingly, that is, the latitude and longitude range of each virtual node is known. As shown in Figure 1, when the partial parameters of the constellation are (5,12), the earth sphere is divided into a logical grid of 2*5*12.

Rule 1: Choose the prime meridian as the starting line, and take the positive direction from south to north and from west to east.

Rule 2: According to the number N of orbital planes and the number of satellites M in each orbital plane, divide the earth sphere into 2*N*M logical grids, each grid is a virtual node.

Rule 3: Each virtual node is uniquely determined by the number <n,m> of the lower left corner vertex. For example, the virtual node determined by the polygon ABCD area in the figure is uniquely marked by the number of point C <n,m>=<1,3>.

Rule 4: After the virtual node network is determined, the mark of each virtual node uniquely corresponds to a set of <longitude, latitude> values, namely

In an inclined orbit constellation, looking down from above the North Pole, the right ascension points of the ascending nodes of the N orbital planes are evenly distributed within a 2π circle in the plane where the equator is located. For the Walker constellation with parameter i:T/N/F, assuming that the ascending node right ascension at the initial moment of the first orbital plane is Ω ₁ , and the initial phase angle of the satellite node numbered 1 in the first orbital plane is ω _{1 , 1} , then the ascending node right ascension and phase angle of all satellite nodes in the constellation can be calculated by formula (1).

After the ascending node right ascension and phase angle of the satellite node are determined, the position of the satellite node in the equatorial inertial coordinate system at any time and its Corresponds to the latitude and longitude on the ground. Then, from the longitude and latitude of the virtual node and the longitude and latitude of the satellite node in Rule 4, it can be easily determined which satellite is responsible for the communication task in the area of the virtual node.

According to the virtual node topology strategy, if the satellite network is abstracted into a large switching node, it can be considered that the source and destination nodes of the ground request are fixed relative to the satellite network. After introducing the virtual node, as shown in Table 1 and Table 2, add the virtual node tag where the CS node is located in the relationship record between the content of the FIB table and the storage node, and add the virtual node where the port is located in the relationship record between the content and the forwarding port in the PIT table. mark. At the same time, the FIB and PIT table are managed by the high rail controller, and the update of the PIT table is dynamically updated with the arrival of the request and the return of the data;

Table 1

Table 2

The update mechanism of the on-board FIB table is described as follows: The FIB table records the mapping relationship between content caches and cache nodes in the network, and is one of the key technologies to improve the response speed of content requests. Different from the creation and maintenance of the ground FIB table, the present invention divides the on-satellite FIB into satellite node cache records and ground node cache records. The former is NULL in the virtual node number in the FIB table, and the latter is the virtual node number where the cached content is located. As for the maintenance of the satellite node cache map, the present invention adopts the mechanism of combining event driving and polling, and the update process is shown in FIG. 2 . In the event-driven mechanism, when the request data is returned to the satellite node, there must be no record of the content name in the FIB (the reason will be explained in the routing design). At this time, the controller actively updates the FIB table. When the switch replaces a certain content by performing a cache replacement operation, the switch actively announces the change, and the controller updates the FIB table. The controller needs to collect the resources of the switch node through polling. During this process, if the controller initiates a polling request to a node, the timer expires and no ACK is received, the controller considers the node to be invalid. , the controller updates the FIB table and marks the content name record associated with it as invalid. When record replacement occurs in the FIB table, the marked record will be replaced first.

Fig. 3 is the virtual node routing state diagram of adaptive ICN and IP request. When the ground node initiates a request to the low-orbit switch node, the switch node matches the request according to the flow table, and directly forwards the request if the match is successful. Otherwise, the node matches the request type according to the flow table and extracts the source, destination IP address or virtual node information according to the request type, and the controller executes the virtual node-based routing algorithm according to these information. After the forwarding path is generated, the controller sends it to the relevant switch node, and the switch node performs the forwarding action. When the data is returned, the controller generates the return path of the data object according to the PIT table, and executes the caching of the content according to the cache replacement strategy and adds records to the FIB table. It should be pointed out that for the content cached on the satellite node, because the high-orbit controller is sensitive to the content (through the FIB table), the controller will directly generate a return path for the content cached on the satellite and send it to the switch. node. For the content cached on the ground network, there is no record of content changes in the FIB when the request passes through the satellite network. When the data is returned to the satellite node, it needs to be re-routed. This process is completed by the high-orbit controller. At this time, the controller will update the FIB. surface. In the process of request and data object forwarding, the high-orbit controller will detect the link status according to the time slice, so as to solve or avoid link congestion; when a satellite node fails, its predecessor node will re-request control after the request times out. A new path is generated, but the route does not need to start from the source node.

When ICN requests and data returns are transmitted through the satellite network, the transmission paths of Interest packets and data objects need to be calculated by the controller according to the routing policy. According to the introduction of the above virtual nodes, as shown in Figure 1, when data is transmitted between virtual nodes <2,5> and <5,3>, because each virtual node is responsible for communication with the nearest satellite, the data transmission The path can be converted from the calculation of the satellite node path to the calculation of the virtual node path. There are two possibilities for caching the requested content, one is that the content is cached on the ground node; the other is that the content is cached on the satellite node. In the first case, the data return path is calculated by the virtual node where the source and destination nodes are located; in the second case, the virtual node where the node is located is obtained according to the running trajectory of the satellite node, and the routing calculation is transformed into the first case .

The conditions and definitions of virtual route calculation are as follows:

1. It is assumed that the initial processing capacity of all satellite nodes is the same.

2. Each satellite node keeps the link connected in the direction of the four domains, and it is assumed that the reverse seam is not considered.

3. The maximum communication amount of the satellite node S _dmax (i): the maximum amount of data transmitted by the satellite node i per unit time.

4. The maximum communication volume of the virtual node D _<n,m> : the maximum amount of data transmitted by the virtual node in unit time, that is, the sum of the maximum communication volume of all satellite nodes in the same orbit.

5. Virtual node load rate γ _<n,m> : the ratio of the sum of data transmitted by all satellite nodes passing through the virtual node in unit time to D _<n,m> . where data(j) represents the data transmission volume of satellite node j per unit time.

6. Link weight w _<n,m> : The link weight reflects the ability of intra-orbital and inter-orbital interplanetary links to transmit data. Defined by formula (4), the first part is the reciprocal of the end-to-end transmission time of 1bit data, L _<n,m> is the length of the interstellar link <n,m>, assuming that the data is transmitted in the vacuum at the speed of light C ( The unit is bit m/s); the second part is the availability of the bandwidth of the interstellar link <n,m>, s _<n,m> is the remaining amount of the bandwidth of the interstellar link <n,m>, and B is the interstellar link The maximum value of the bandwidth of the road <n,m>; α is the link weight adaptive factor, and its value range is between (0, 1), and the controller automatically adjusts the value of α according to the link bandwidth utilization rate.

7. Definition of routing matrix: let N=5, M=7, then the logical network structure of the virtual node is as shown in the figure. It is assumed that the virtual node coordinates of the source and destination nodes returned from the data searched from the PIT table are <n ₁ , m ₁ > and <n ₂ , m ₂ >.

1) If v=v ₁ , o=o ₁ , the transmission path is generated in a matrix with virtual node coordinates <n ₁ , m ₁ > and <n ₂ , m ₂ > as diagonal vertices, as shown in Figure 4. The matrix is A-A3-B-B1.

2) If v=v ₂ , o=o ₁ , at this time, due to the characteristics of the links in the track forming a loop, in the logical network, the routing matrix is transmitted in the vertical direction, and the transmission path is still in the virtual node coordinate <n ₁ , m ₁ > and <n ₂ , m ₂ > are generated in the matrix of diagonal vertices. As shown in Figure 4, when the source and destination nodes are A and C, the routing matrix is a semi-circular matrix A-A1-C2-C1 -C-C3-A2-A3.

3) If v=v ₁ , o=o ₂ , then the routing matrix is looped in the horizontal direction. As shown in Figure 4, when the source and destination nodes are A and D, the routing matrix is a half-loop matrix A-A4- D1-D-A6-A5.

4) If v=v ₂ , o=o ₂ , then the routing matrix is transmitted in both vertical and horizontal directions. As shown in Figure 4, when the source and destination nodes are F and E, the routing matrix is the loopback matrix F. -E1-E-F1.

Assuming that data is transmitted from point A to point B, an undirected graph matrix G=(V, Y, W) is obtained according to the definition of the routing matrix, where V is the set of virtual nodes, and Y is the set of virtual node load rates. The formula (3) Determine, W is a set of link weights between satellite nodes responsible for virtual node communication, determined by formula (4).

The specific implementation steps of the optimal path algorithm based on virtual routing matrix are as follows:

S1: Calculate the maximum communication amount according to the virtual node information.

S2: Calculate the routing matrix according to the node information.

S3: Calculate the load rate and link weight matrix of the virtual nodes in the routing matrix according to the routing matrix and the traffic of the virtual nodes.

S4: Construct an undirected graph matrix according to the above information.

S5: Calculate the optimal path according to the virtual node load rate and the link weight matrix.

S6: Calculate the temporary nodes and permanent nodes in the current working node state.

S7: Add the working node to the path set S, if the destination node has been found, end the procedure, otherwise go to S6.

Aiming at the deficiencies of the existing satellite network routing algorithms and the new features provided by SDICSN on the satellite network, the VDMR routing algorithm is proposed under the SDICSN architecture in this embodiment. The idea of virtual node topology is used to design the division rules for ground virtual nodes. The parameters of the satellite network constellation number the satellites, and the one-to-one correspondence between the virtual nodes and the satellite nodes is determined by the longitude and latitude of the virtual nodes and the longitude and latitude of the satellite nodes mapped to the ground. According to the operation law of the satellite network, this paper proposes a virtual routing algorithm, which generates a routing matrix based on the relative positions of the source and destination nodes in the satellite network, thereby reducing the complexity of routing calculation.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. The equivalent replacement or modification of the created technical solution and its inventive concept shall be included within the protection scope of the present invention.

Claims (1)

1. a routing method based on SDN and ICN satellite network architecture, is characterized in that, comprises following concrete steps: Step 1, divide virtual nodes; Step 2, design FIB and PIT table based on virtual nodes; Step 3, update the FIB table mechanism; Step 4: When the ground node initiates a request to the low-orbit switch node, the switch node matches the request according to the flow table, and directly forwards the request if the match is successful; otherwise, the node matches the request type according to the flow table and extracts the source, destination IP address or Virtual node information, the controller executes the routing algorithm based on the virtual node; Step 5: After generating the forwarding path, the controller sends it to the relevant switch node, and the switch node performs the forwarding action; when the data returns, the controller generates the return path of the data object according to the PIT table, and executes the content according to the cache replacement policy The cache also adds records to the FIB table; The specific way of dividing virtual nodes in step 1 is as follows: R1: Select the prime meridian as the starting line, and take the positive direction from south to north and from west to east; R2: According to the number of orbital planes N and the number of satellites M in each orbital plane, divide the earth sphere into 2*N*M logical grids, each grid is a virtual node; R3: Each virtual node is uniquely determined by the number <n,m> of the vertex in the lower left corner; R4: After the virtual node network is determined, the label of each virtual node uniquely corresponds to a set of <longitude, latitude> values, namely

In the inclined orbit constellation, looking down from above the North Pole, the right ascension points of the ascending nodes of the N orbital planes are evenly distributed in a 2π circle in the plane where the equator is located; for the Walker constellation with the parameter i:T/N/F, it is assumed that the first The ascending node right ascension at the initial moment of each orbital plane is Ω ₁ , and the initial phase angle of the satellite node numbered 1 in the first orbital plane is ω _1,1 , then the ascending node right ascension and phase angle of all satellite nodes in the constellation Calculated by the following formula:

In the formula, T is the total number of satellites on the Walker constellation; F is the phase factor; In step 2, the design of FIB and PIT table based on the virtual node is as follows: according to the virtual node topology strategy, the satellite network is abstracted into a large switching node, and the source and destination nodes of the ground request are fixed relative to the satellite network; Add the virtual node tag where the CS node is located in the relationship record between the content of the FIB table and the storage node, and add the virtual node tag where the port is located in the relationship record between the content and the forwarding port in the PIT table. The update of the PIT table is dynamically updated with the arrival of the request and the return of the data; In step 3, an event-driven and polling mechanism is used to update the FIB table mechanism, specifically: in the event-driven mechanism, when the request data is returned to the satellite node, the controller actively updates the FIB table; When a certain content is replaced, the switch actively announces the change, and the controller updates the FIB table; the controller collects the resources of the switch node by polling. During this process, if the controller polls a node After the request, after the timer expires and no ACK is received, the controller considers the node to be invalid, and the controller updates the FIB table and marks the related content name record as invalid; when the record replacement occurs in the FIB table, it will be replaced first. marked records; The routing algorithm based on virtual nodes is as follows: Assuming that the initial processing capabilities of all satellite nodes are the same, and each satellite node remains connected in the direction of the four domains, there are: S1: Calculate the maximum traffic D _<n,m> of the virtual node:

S2: Calculate the virtual node load rate γ _<n,m> ;

where data(j) represents the data transmission volume of satellite node j per unit time; S3: Calculate the link weight w _<n,m> , the link weight reflects the ability of intra-orbital and inter-orbital interplanetary links to transmit data; S4: Define the routing matrix; The link weight w _<n,m> calculated in S3 is specifically:

The first part is the reciprocal of the end-to-end transmission time of 1bit data, L _<n,m> is the length of the interstellar link <n,m>, C is the speed of light transmitted in the vacuum; the second part is the interstellar link <n,m> bandwidth availability, s _<n,m> is the remaining bandwidth of the interstellar link <n,m>, B is the maximum bandwidth of the interstellar link <n,m>; α is the link weight self Adaptation factor, whose value range is between (0, 1), the controller automatically adjusts the value of α according to the link bandwidth utilization; The routing matrix is defined in S4:

1) If v=v ₁ , o=o ₁ , the transmission path is generated in a matrix with virtual node coordinates <n ₁ , m ₁ > and <n ₂ , m ₂ > as diagonal vertices; 2) If v=v ₂ , o=o ₁ , at this time, due to the characteristic that the links in the track form a loop, in the logical network, the routing matrix is transmitted in the vertical direction, and the transmission path is still in the virtual node coordinate <n ₁ , m ₁ > and <n ₂ , m ₂ > are generated in the matrix of diagonal vertices; 3) If v=v ₁ , o=o ₂ , at this time, the routing matrix is transmitted in the horizontal direction; 4) If v=v ₂ , o=o ₂ , at this time, the routing matrix is transmitted in a circular direction in both the vertical direction and the horizontal direction.

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